Single-Crystal III-Nitride Ferroelectric Gate Stack for Stable Switching
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Solution Overview
Problem
Existing ferroelectric memory devices using polycrystalline III-nitride ferroelectric materials suffer from stochastic switching behavior and potential charge leakage due to grain boundaries, which affects their switching characteristics and reliability.
Innovation Solution
The implementation of a semiconductor structure with a single crystalline III-nitride ferroelectric plate, grown epitaxially between the gate electrode and the gate dielectric layer, which allows for predictable and simultaneous switching of dipole moments under an external electrical field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polycrystalline III-nitride ferroelectric material is used, then manufacturing is easier, but stochastic switching behavior and charge leakage occur due to grain boundaries
Solution Approach 1:
The patent changes the crystalline structure parameter from polycrystalline to single-crystalline III-nitride ferroelectric material. This parameter change eliminates grain boundaries while maintaining the ferroelectric properties, thereby resolving the contradiction between ease of manufacture and reliability by improving switching characteristics and eliminating charge leakage through the crystal structure transformation
Solution Approach 2:
The patent employs a composite structure consisting of a single-crystalline III-nitride ferroelectric layer integrated with semiconductor devices. This composite approach combines the advantages of single-crystalline material (no grain boundaries, reliable switching) with the functionality of ferroelectric memory devices, achieving both manufacturability and high reliability
2Reliability
If single crystalline III-nitride ferroelectric material is used, then switching characteristics improve, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the single-crystalline III-nitride ferroelectric layer early in the manufacturing process, before subsequent device fabrication steps. The layer is grown epitaxially on a substrate with appropriate crystal orientation, establishing the reliable ferroelectric foundation before any device structuring occurs, thereby managing complexity through process sequencing
Solution Approach 2:
The patent uses an intermediary substrate with a specific crystal structure (such as sapphire or silicon carbide) that facilitates the growth of single-crystalline III-nitride ferroelectric material. This intermediary serves as a template that enables single-crystalline growth while simplifying the overall manufacturing process by providing a ready-made crystalline foundation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of single crystalline III-nitride ferroelectric material improves switching characteristics by eliminating stochastic variations and reducing charge leakage, thereby enhancing the reliability and performance of ferroelectric memory devices.
Implementation Method 1
A ferroelectric material refers to a material that displays spontaneous polarization of electrical charges in the absence of an applied electric field. The net polarization P of electrical charges within the ferroelectric material is non-zero in the minimum energy state.
Implementation Method 2
Thus, spontaneous ferroelectric polarization of the material occurs, and the ferroelectric material accumulates surfaces charges of opposite polarity types on two opposing surfaces.
Implementation Method 3
epitaxially growing a single crystalline III-nitride ferroelectric layer in epitaxial alignment with the single crystalline III-nitride compound semiconductor material layer
Data Source
AI summary
A semiconductor structure includes an active region including a source region, a drain region, and a channel region extending between the source region and the drain region, a gate stack, and a gate dielectric layer located between the gate stack and the active region. The gate stack includes an electrically conductive gate electrode and a single crystalline III-nitride ferroelectric plate located between the electrically conductive gate electrode and the gate dielectric layer, and an entirety of the single crystalline III-nitride ferroelectric plate is single crystalline.